Round slings are predominantly used in industry, in the building trade and in industry for lifting loads. Lifting belts are used in many ways in the transportation industry and especially in branches of building.
According to U.S. Pat. No. 4,210,089, a round sling is known which includes two chambers, in order thereby to obtain higher strength and improved resistance to abrasion and cutting.
According to U.S. Pat. No. 5,238,278, a textile round sling is known, with additional ribs on the round sling tube, which thereby is to effect an improved cutting and abrasion resistance.
According to U.S. Pat. No. 5,651,572, a round sling is known which includes an additional strand of optical cables, in order to be able to emit a signal when there is a break.
According to U.S. Pat. No. 4,843,807, a method of production of round slings is known, which relates to a rational production of a round sling.
According to U.S. Pat. No. 5,498,047, a lifting belt is known which consists of a woven band, with loops and at least one reinforced edge, which is to protect against premature wear. An additional textile inlay is concerned as the reinforcement.
The following points are disadvantageous in round slings and lifting belts:
Round slings are manufactured from a tube, which normally consists of one chamber, but can also consist of two chambers as in U.S. Pat. No. 4,210,089. Round slings are manufactured from endless yarn strands, which always give a round, endless ring or round tube, which can, however, be designed in their dimension such that they can lift loads of up to 100 t. Since round slings give an endless ring, they cannot easily be passed under a stationary load object.
Lifting belts are manufactured from woven belts, which according to width and thickness can normally lift loads of up to 20 t. Lifting belts are sewn together to form one piece with two-sided loops. This band can be pulled through under a stationary load and suspended with the loops into a load hook on both sides. Since the bands are under strong stress due to the load, they are very susceptible to wear and cuts. It is frequently sought to eliminate this disadvantage with a costly coating.